*Spoiler*
As the fight the the leader of the cult we find out that he has moved through time three times. The first, when he met Sylvia for the first time and fell in love with her, she rejects his feelings. So he make a plan and steals the demon King's power, then use it to make Sylvia reincarnate "eternally". He then follows her reincarnated body and controls everybody around her to hate her to leave her lonely and deprived of love, so that she would fall in love with him. Doesn't work, so the third time is where the main story starts, she has her pass memories of her original life (when she was sick) and her second life as Sylvia. Leaving out when they first met, this time his plan is to let her have those memories, allow her to make connections and then take it all away from her.
*So her family does love her but they were mind controlled the first time to not love her, they were being used as puppets.
Did the father apologized for hurting sylvia? I dropped it so…. It was getting kinda annoying how they suddenly acted like she’s part of the family before FL got transmigrated to sylvia’s body. They were straight up acting like she’s so pathetic and irrelevant but then she started having powers and acting cold to the father and all of a sudden the father starts caring for her? Hmmm bullshit